Read through the forum first for more info, but you can do a 70:30 ratio of hardwood leaf mulch and well decayed hardwood. If the wood is not decayed to the point where you can break it apart easily with a screwdriver, or even better, your hand, then it is not good enough yet. Mix that throughly and let it dry. If possible, blend it (this is by personal preference, but I find it to work better for me), and strain it through a metal mesh screen to remove the bigger particles. Fill your 10 gal tank 1/3rd of the way with the fine particles you strained (after blending), compact it by hand or with a flat tool. The rest can be filled with the non strained sub.
10 Gal always seem a little shallow for my taste, the only exception I can think of is a 10 Gal TALL, not the long horizontal style.
Have fun with them, they are great beetles to keep.